The present invention is directed to a tool holder for a drilling device or a chiseling device and includes a guide tube for receiving a drilling or chiseling tool and the tool has a cylindrically shaped shank end which is inserted into the guide tube. The shank end has at least one axially closed depression or recess for receiving a locking element. Radially displaceable locking elements are arranged in openings extending radially through the guide tube so that the elements can engage in the recesses in the tool shank. An adjusting sleeve laterally encloses the guide tube and is rotatable relative to the tube and includes recesses which can be placed in registration with the openings through the guide tube.
In addition to devices which are used only for drilling or chiseling operations, percussion drilling devices and hammer drills are known in which the tool inserted into the device experiences a rotational movement and a percussive movement, particularly for work in rock. While it is possible in percussion drilling machines to use drill chucks which are adjustable in diameter and clamped in a friction-locking manner because of the relatively low output, tools with a selected unit diameter for the shank end so that locking elements can engage with the tool in a form-locking manner are conventional in hammer drills and chiseling devices. The locking elements hold the tools so that axial movement is possible while transmitting rotational movement to the tool.
A known tool holder includes an adjusting sleeve which is rotatable relative to the guide tube and has recesses arranged to line up with the locking elements. To replace a tool, the adjusting sleeve is brought into a position where the locking elements can move partially radially outwardly into the recesses. Accordingly, a partial rotation of the adjusting sleeve is required in the known tool holder.
In practice, this known type of tool holder has proved to be disadvantageous. To turn the adjusting sleeve a corresponding countertorque must be applied to the drilling or chiseling device. As a result, the person operating the tool must use both hands to effect the rotation of the adjusting sleeve. Therefore, in such an operation the operator must temporarily let go of the device with one hand to pull the used tool out and replace it with a new one. After inserting the new tool, the adjusting sleeve must be rotated back into the locked position of the tool. Such steps are involved and time-consuming. For handling ease, as well as saving time, it is conventional in practice to rotate the adjusting sleeve into its released position with the tool holder directed downwardly, whereby the tool can drop out of the tool holder due to its own weight. If the tool is allowed to drop, however, it can lead to damage to the tool or injury to the operator.
In another known tool holder the adjusting sleeve is axially displaceable against a restoring force. In this type the tool holder is usually unlocked by pulling the adjusting sleeve in the axial direction. To apply the corresponding reaction force, the device must be supported on the body of the operator or on a support base. The operator's other hand can remain free for replacing the tool. When cylindrical locking elements are used in this type of tool holder, the tool holder usually results in a considerably longer length than that of the above type. Moreover, vibrations developed during the operation of the device can impair the functioning of the tool holder.